While researching for some concrete informations regarding another thread I found the following issues about the advantages of air launches. May be that they have been mentioned already but it not that decisively, concretely and detailed as far as I remember.

... there are fewer delays waiting for specific launch windows (to match desired orbits) because the vehicle can be flown to an alternate launch point that is better aligned with the desired orbit. In addition, ground launches must be postponed whenever ships enter the ocean zones near the coastal launch sites or where rocket stages are expected to drop; the QuickReach carrier aircraft can avoid such delays by flying to a different release point.

Air launching also simplifies the design of the vehicle, which simultaneously ... improves reliability. The modest performance gain of launching at 25,000 to 35,000 feet, and with some forward speed, makes it easier for a two-stage rocket to put payloads into orbit. In addition, the first stage engine and nozzle can be designed solely for operation at a significant altitude – this avoids the design challenges of also needing to operate efficiently at sea level air pressure during lift-off.

Hitch being, it's also a lot heavier. A traditional rocket only has to withstand stress in the vertical direction -- the direction along which a cylinder is strongest. An air-launched rocket, on the other hand, has to be able to make the initial climbing turn, under a reasonably high g-load (something like 3 or 4 is probably a good guess), that would make the mighty Saturn V undergo a RUD event.

...enter the T/LAD method, which does it at a fraction of the energy with a nylon cord.

You could also do it a bit more slowly, without wings and with minimal lateral loading using your gimbal-steering or something like that; you'd have to get a good pitch from your dropship to make it happen, but as I have said before, it was done with a minuteman missile and a C-5 using a cargo sled and a drougue chute. That is essentially the same method AirLaunch wants to use (only with a C-17 'cuz QuickReach is smaller than a Minuteman).

I like Truax's sea launch better myself. He had a rocket of more modest size called Excalibur that could put 50 tons in LEO. This would also use pressure-fed tech--would need no launch pad--no airplane...and is self-erecting.

John London at Marshall (author of LEO ON THE CHEAP), and Bill Sprague of AERA are among the few big pressure-fed advocates aside from Beal and the old AMROC crowd with their hybrids which the orbital version of Dream chaser might use.

I am not just saying this due to a falling out with Gump--but sea-based is the way to go. You can take your time with this launch method--and have a bigger rocket than even AN-225 could carry.

Things can happen real fast to an airplane in flight. Boating has a slower pace, and you have time to think about things.

I think that SpaceDev has made a good decision by changing from the X-34 to the HL-20 and reducing the number of people it can carry is also a good idea when looking at crew rotations for the ISS.

Not sure whether NASA will fund its development though, I think that Jim Benson will have to look elsewhere for the cash.

One interesting point is that he talks about a suborbital vehicle for $20m and an orbital version for an additional $100m, a quarter of what T-space is asking for, is it really possible to do it that cheaply. Even SSO is reputed to have cost $25m can SpaceDev reasonably expect to build the 6 man suborbital Dream Chaser plus the large hybrid boosters for $5m less?

I think, with the new Air Force deal, + other projects (as SS1) etc, they have experiance, technology available others don't have.

So I think $20m is "possible", but I guess it may cost more than initialy planned (as many projects do). But even $30m isn't gigantic. I do hope.. they will find someone interested with a lot of money... but this can be difficult.

The air force deal will no doubt help but the boosters for dream chaser are quoted as being 10 times more powerful than the 100,000 lb thrust ones the air force is financing, also I'm not sure whether the airforce booster will be designed to operate in clusters.

_________________A journey of a thousand miles begins with a single step.

Regarding the $5 million less than the funds for SS1 SpaceDev may get an advantage Scaled Composites/Mojave Aerospace Venture had no chance to get: The production of Virgin Galactic's five vehicles will cause enhancements of the production capacities of the companies who produce materials, elements and components for The Spaceship Company.

...well, personally I don't think that the fiscal numbers are realistic. I would almost say that they are irresponsible, but I haven't actually seen the study itself, so I can't make a definitive statement. However, basing a program (as described) on the notion of "emerging technologies that will be available by the time they are needed" is a setting your course into a quagmire of project delays and surprise cost overruns.

It's also comparing apples to oranges, considering that Constellation is a project to develop and field a Manned Interplanetary Exploration Architecture, not simply "get to the moon on a vectored-thrust ultralight" and I expect that if the SpaceDev study had included the capacity to send humans to Mars, then the glib notion of "one tenth the cost!" would have been scaled back or absent.

In the end, this begins to read like "NASA-bashing for the purposes of increasing the circulation of our press release," a practice which I find unsavory within this industry and which I would like to see stop. It is something Musk has largely refrained from doing and I think that provides him with a great deal of clout and credibility, and places him on the inside track for actually landing one of Griffin's commercial contracts.

Anyway, I thought it was ironic that the boys from Poway would make this release right after publi said he liked them. Our buddy is gonna have a conniption. Rightly so, in my view.

Speaking of SpaceDev and SpaceX, I read that SpaceDev is buying a Falcon I mission.